This invention relates to high-density circuit assemblies that use heat sinks to facilitate component cooling and specifically to such circuit assemblies where component-bearing carrier plates are pressed against heat sinks by platens.
A known assembly, from the present applicant's Offenlegungsschrift (German laid open application) DE-A 4 111 247, includes a circuit assembly incorporating a heat sink. A carrier plate has components to be cooled by heat transfer to the heat sink. The carrier plate is pressed against the heat sink by a platen. The platen has a resilient cushion element which faces, and is pressed against, the carrier plate to insure good thermal contact between the carrier plate and the heat sink.
In the applicant's supplementary patent application P 41 22 428, another known circuit assembly includes a platen with a rigid mounting element and a rigid bridge element, with an resilient cushion element between them.
In both, of the above-mentioned prior art assemblies (DE-A 4 111 247 and P 41 22 428), and other circuit assemblies shown in Offenlegungsschrift DE-A 35 09 456 and DE-A 35 21 572, the carrier plates and their components are virtually inaccessible. A first side of the carrier plate is adjacent to the heat sink. Because it is desirable to maintain good thermal contact between components on the carrier plate and heat sink, the heat sink must essentially cover a first side of the carrier plate and any heat dissipating components on that side. The carrier plate is pressed from the second side of the carrier plate to the heat sink to insure good thermal contact between tile carrier plate and the heat sink. The device used to press the carrier plate generally covers the second side. Thus, both sides of the portion of the carrier plate containing the power-dissipating components are essentially covered leaving the components thereon virtually inaccessible. Therefore, modification of the overall circuit assembly can be very difficult. The same problem exists with, for example, the circuit arrangement known from Offenlegungsschrift DE-A 35 09 456 or DE-A 35 21 572.
Still another known circuit assembly from Patentschrift (German Patent) DE-C 36 28 556, includes at least one semiconductor wafer with semiconductor circuit elements on it. The semiconductor wafer rests on a base plate. Conductor elements around the periphery of the wafer are wired to the semiconductor circuit elements. The semiconductor circuit elements are fully encapsulated in insulation material, and the conductor elements, partly so. Contacts of time conductor elements protrude through the insulation material on a side facing away from the base plate. Surfaces of the protruding contacts lie in a single plane. The protruding contacts are thereby available to make electrical contact by pressing against a contact plate on another part such as a circuit board. Because the circuit elements are encapsulated in the insulation material, they are not susceptible to modification. Therefore, this semiconductor assembly permits no convenient modification of semiconductor components.
A semiconductor assembly of hybrid structure is described in Offenlegungsschrift DE-A 3 643 288. This semiconductor component assembly permits a high degree of integration. The structure also permits electrical pretesting of all components prior to final assembly. Additionally, the structure permits the simple fastening of components to the carrier plate and electrically coupling the components to external circuits.